The objective of this research is to characterize the cerebral sequelae of traumatic brain injury (TBI) as a function of age, in a basic science animal model. TBI is one of the leading causes of mortality and long-term morbidity in adults and children. In infants, the consequences of head injury are particularly severe and the clinical course is different from adults. Although the effects of TBI have been well documented in adult animal models, less data have been reported on these effects in the infant/juvenile or the mechanisms underlying such changes. Cerebral blood flow is thought to contribute to neurologic outcome, thus often is an important therapeutic target. The Aims of the proposed studies will include a characterization of the age dependent effects of TBI on cerebral blood flow and mechanisms contributory to such changes in an animal model designed to mimic concussive brain injury. Outcome measures will include physiologic parameters (blood flow), biochemical (brain parenchymal changes in putative modulators/mediators of injury), histopathologic (neuronal cell loss), molecular (expression of modulators/mediators of injury), and pharmacologic parameters (receptor density/regulation). These studies may lead to new therapies for brain-injured individuals. [unreadable] [unreadable]